X-ray screen



M. B. EVANS X-RAY SCREENV Filed DeO. 26, 1928 m, V5. @u 5 6 Feb. 23,1932.

Patented Feb. 23, 1932 UNITED STATESA MAYNARD IB. EVANS, F DETROIT,MICHIGAN X-RAY SCREEN Application filed December 26, 1928. Serial No.328,482.

ation and use, as more fully hereinafter set forth.

In the drawings annexed- Fig. l is a face view of the screen;

Fig. 2 is a longitudinal sectional view on the line 2 2 of Fig. l;

Fig. 3 is a transverse sectional view on the line 3-3 of Fig. l.

Referring to the drawings annexed by reference-numerals, 5 designatesthe usual calcium tungstate screen-sheet. Usually, the tungstate face ofthis sheet is coated permanently with a thin layer of Celluloid for thepurpose of protecting the tungstate, this celluloid material being usedbecause it does not interfere with the fluorescent action. As is wellknown, in use the X-ray film is placed between two of these screens withthe cellu- 5 loid faces of the two screens next to the film.

With my invention, I do not affix permanently the Celluloid lilm to theface of the tungstate, but instead thereof I employ a separate,removable sheet 6 of thin Celluloid material and temporarily fasten thesame to the screen by means of a sheet of cardboard 7, preferably lO-plycardboard, the four marginal portions of the Celluloid sheet beingfolded over the edges of the backing-board and 3 fastened to the backthereof by being pasted thereto throughout their lengths, thus formingan envelope in which the screen is entirely enclosed. The backing-board7 is made n longer as well as wider than the screen 5.

This screen is used in the same manner as the screens now in generaluse, and some of its advantages over the screens now in general use areas follows: The thin separate sheet of Celluloid 6 affords even betterprotection than the permanent coating of Celluloid heretofore used inthat it not only protects the entire face of the screen but also itsedges, thereby preventing the face and edges of the screen from beingscratched or chipped while being 0 handled and shipped. This Celluloidsheet also `serves to hermetically seal the screen, to thereby preventdrying out of the screen. The backing-board prevents breaking andbuckling and warpingof the screen, particularly in view of the fact thatthe backingboard is cut sufficiently larger than the screen to have allfour of its margins project beyond the four edges of the screen, wherebythe celluloid sheet may be stretched tightly over the cardboard withoutcausing buckling or warping should the Celluloid shrink, it beingobvious that shrinking of the Celluloid would Cause distortion of thescreen if the backing-board were of such size as to permit the shrinkingaction of the Celluloid to press l5 against any two opposite edges ofthe screen.

It will be obvious also that, by reason of the fact that the thinCeluloid sheet may be stretched tightly and smoothly on the face of thescreen, it will not permit blurring by 7u filtration of violet rays;and, further,'that this Celluloid protecting Covering can be readilyremoved when the covering becomes dirty or discolored by age by merelytearing or slitting it suiciently to remove the screen. Also it will beseen that this manner of Covering the screen renders it more nearlywaterproof, since it not only covers the face of the screen but also theedges, and the backingboard too assists in preventing moisture get- '8Uting access to the screen.

lrVhat I Claim as new is:

l. An X-ray screen embodying a iiuorescent plate, a backing-boardpervious to X- r rays and having its area larger than the plate 8 tothereby extend beyond the edges thereof, and a separate sheet ofCelluloid stretched smooth on the face of the plate and having itsmargin portions folded over upon the back '90 side of the board andpasted thereto, to thereby provide a removable protective envelope forthe screen which completely seals it against ingress and egress ofmoisture.

2. An X-ray screen embodying a fluorescent plate having stretchedsmoothly on its face a removable separate sheet of Celluloid, and abacking-board for the plate, the marginal portions of said Celluloidsheet being folded over the edges of the sheet and of the lo" board andpasted to the back face of the latter.

3. An Xray screen embodying a fluorescent plate, a backing-boardpervious to X- rays, and a thin, separate, removable sheet of materialtransparent to the light rays from the crystals of said plate, saidsheet of material bein stretched over the face of the plate an beingsealed at its edges to said backing-board.

In testimony whereof I hereunto aiix my signature.

MAYNARD B. EVANS.

